Is it a matter of retribution? If Trump issues an order that Congress didn't like, what could they do? Their job is to create laws, not interfere with the enforcement thereof.
> If Trump issues an order that Congress didn't like, what could they do?
In terms of substantive, direct, responses (e.g., excluding retaliating against other Presidential initiatives and appointments), major notable options include:
(1) Expressly prohibit the things called for in the order by legislation (overriding a veto, of necessary);
(2) Sue the administration claiming the order violates existing (statute or Constitutional) law;
They could pass laws that override the order, or, which was what happened constantly during Obama's turn, simply vote against all directives put forward by the president and his party as a sign of disapproval. They can also vote to strip resources from organizations tasked with carrying out executive orders. Now, Trump's most recent orders have lined up very well with the extreme end of the right wing, so they aren't going to try to stop him.
In terms of substantive, direct, responses (e.g., excluding retaliating against other Presidential initiatives and appointments), major notable options include:
(1) Expressly prohibit the things called for in the order by legislation (overriding a veto, of necessary);
(2) Sue the administration claiming the order violates existing (statute or Constitutional) law;
(3) Impeach and remove the President.